Studies on the Enzyme Reaction Mechanism of Cytochrome P450

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Cytochrome P450 and its electron transfer system play an important role in metabolizing biomolecules and xenobiotics. The P450 enzyme catalyzes the oxidation of various substrates by the introduction of one oxygen atom into a substrate from dioxygen. Our research projects concerning the oxidation system are shown below.(1) Much interests have been focused on the mechanism of the electron transfer between the flavin and the heme. Hence, intramolecular linked flavin- porphyrin complexes have been prepared to elucidate the flavin-heme electron transfer and its transient nature. Furthermore, N-benzyl-1,4- dihydronicotinamide compounds have been synthesized as the model of NAD(P)H coenzyme. Then, the steric and electronic effects have been discussed based on UV spectra and redox potential data.(2) P450 enzyme model systems have been studied to reveal the enzyme mechanism of P450. Furthermore, polypeptide-bound Fe(III)TPPCl has been prepared to consider environmental effects of protein around hemin in P450.(3) In cytochrome P450 monooxygenations, metalloporphyrin oxenoid complex is considered to be an ultimate reactive species which is responsible for the oxidation of substrates. In the research, the formation mechanism of the metalloporphyrin oxenoid via acylperoxy metalloporphyrin was proposed.